Neuronal Calcium Sensor-1 (Ncs1p) Is Up-regulated by Calcineurin to Promote Ca2+ Tolerance in Fission Yeast
Neuronal Calcium Sensor-1 (Ncs1p) Is Up-regulated by Calcineurin to Promote Ca2+ Tolerance in Fission Yeast
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DOI：
10.1074/jbc.m109.058594
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发表时间：
2010-02-12
影响因子：
4.8
通讯作者：
Ames, James B.
中科院分区：
文献类型：
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作者：
Hamasaki-Katagiri, Nobuko;Ames, James B.
神经细胞钙感受器(NCS)蛋白调节信号转导，从酵母到人类都高度保守。裂解酵母(Ncs1p)中的NCS同源物对细胞在极端的钙离子条件下的生长是必不可少的。当裂解酵母生长在细胞外高钙(>；0.1M)中时，Ncs1p的表达增加了100倍。在这里，我们证明了钙离子诱导的Ncs1p的表达是在转录水平上控制的。转录报告分析表明，当细胞外钙浓度升高到0.1M时，NCS1启动子的活性增加了30倍，并且具有高度的钙专一性。钙调神经磷酸酶抑制剂(FK506)和敲除钙调神经磷酸酶靶标prz1可取消ncs1的钙依赖转录。因此，钙离子诱导的Ncs1p的表达与钙调神经磷酸酶/prz1应激反应有关。钙离子响应的ncs1启动子区域由起始密码子上游130个核苷酸组成，包含与Prz1p结合的序列5‘-caact-3’的串联重复序列。钙敏感的ncs1 Delta表型被yam8零突变挽救，提示Ncs1p可能与钙通道Yam8p之间存在相互作用。在Yam8 Delta中，Ncs1p与酵母膜的结合和对Ca2+的摄取均减少，提示钙诱导的Ncs1p与Yam8p的结合导致了通道关闭。我们认为，Ncs1p促进分裂酵母对钙的耐受性，部分是通过细胞内的钙缓冲，可能是通过负调控Yam8p的钙通道。
Neuronal calcium sensor (NCS) proteins regulate signal transduction and are highly conserved from yeast to humans. NCS homolog in fission yeast (Ncs1p) is essential for cell growth under extreme Ca2+ conditions. Ncs1p expression increases similar to 100-fold when fission yeast grows in high extracellular Ca2+ (>0.1 M). Here, we show that Ca2+-induced expression of Ncs1p is controlled at the level of transcription. Transcriptional reporter assays show that ncs1 promoter activity increased 30-fold when extracellular Ca2+ was raised to 0.1 M and was highly Ca2+-specific. Ca2+-dependent transcription of ncs1 is abolished by the calcineurin inhibitor (FK506) and by knocking out the calcineurin target, prz1. Thus, Ca2+-induced expression of Ncs1p is linked to the calcineurin/prz1 stress response. The Ca2+-responsive ncs1 promoter region consists of 130 nucleotides directly upstream from the start codon and contains tandem repeats of the sequence, 5'-caact-3', that binds to Prz1p. The Ca2+-sensitive ncs1 Delta phenotype is rescued by a yam8 null mutation, suggesting a possible interaction between Ncs1p and the Ca2+ channel, Yam8p. Ca2+ uptake and Ncs1p binding to yeast membranes are both decreased in yam8 Delta, suggesting Ca2+-induced binding of Ncs1p to Yam8p results in channel closure. We propose that Ncs1p promotes Ca2+ tolerance in fission yeast, in part by cytosolic Ca2+ buffering and perhaps by negatively regulating the Yam8p Ca2+ channel.